Linking chemical composition and optical properties of biomass burning aerosols in Amazonia

Biomass burning emissions in Amazonia changes the atmospheric composition and aerosol properties during the dry season. We investigated fine-mode aerosol chemical composition and optical properties at an intensive field experiment...

Download Full-text

Long term measurements of aerosol optical properties at a primary forest site in Amazonia

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-2391-2013 ◽

2013 ◽

Vol 13 (5) ◽

pp. 2391-2413 ◽

Cited By ~ 48

Author(s):

L. V. Rizzo ◽

P. Artaxo ◽

T. Müller ◽

A. Wiedensohler ◽

M. Paixão ◽

...

Keyword(s):

Optical Properties ◽

Biomass Burning ◽

Dry Season ◽

Primary Forest ◽

Forest Site ◽

Wet Season ◽

Absorption Coefficients ◽

Aerosol Forcing ◽

Fine Mode

Abstract. A long term experiment was conducted in a primary forest area in Amazonia, with continuous in-situ measurements of aerosol optical properties between February 2008 and April 2011, comprising, to our knowledge, the longest database ever in the Amazon Basin. Two major classes of aerosol particles, with significantly different optical properties were identified: coarse mode predominant biogenic aerosols in the wet season (January–June), naturally released by the forest metabolism, and fine mode dominated biomass burning aerosols in the dry season (July–December), transported from regional fires. Dry particle median scattering coefficients at the wavelength of 550 nm increased from 6.3 Mm−1 to 22 Mm−1, whereas absorption at 637 nm increased from 0.5 Mm−1 to 2.8 Mm−1 from wet to dry season. Most of the scattering in the dry season was attributed to the predominance of fine mode (PM2) particles (40–80% of PM10 mass), while the enhanced absorption coefficients are attributed to the presence of light absorbing aerosols from biomass burning. As both scattering and absorption increased in the dry season, the single scattering albedo (SSA) did not show a significant seasonal variability, in average 0.86 ± 0.08 at 637 nm for dry aerosols. Measured particle optical properties were used to estimate the aerosol forcing efficiency at the top of the atmosphere. Results indicate that in this primary forest site the radiative balance was dominated by the cloud cover, particularly in the wet season. Due to the high cloud fractions, the aerosol forcing efficiency absolute values were below −3.5 W m−2 in 70% of the wet season days and in 46% of the dry season days. Besides the seasonal variation, the influence of out-of-Basin aerosol sources was observed occasionally. Periods of influence of the Manaus urban plume were detected, characterized by a consistent increase on particle scattering (factor 2.5) and absorption coefficients (factor 5). Episodes of biomass burning and mineral dust particles advected from Africa were observed between January and April, characterized by enhanced concentrations of crustal elements (Al, Si, Ti, Fe) and potassium in the fine mode. During these episodes, median particle absorption coefficients increased by a factor of 2, whereas median SSA values decreased by 7%, in comparison to wet season conditions.

Download Full-text

Long term measurements of aerosol optical properties at a pristine forest site in Amazonia

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-23333-2012 ◽

2012 ◽

Vol 12 (9) ◽

pp. 23333-23401 ◽

Cited By ~ 1

Author(s):

L. V. Rizzo ◽

P. Artaxo ◽

T. Müller ◽

A. Wiedensohler ◽

M. Paixão ◽

...

Keyword(s):

Optical Properties ◽

Biomass Burning ◽

Dry Season ◽

Forest Site ◽

Wet Season ◽

Absorption Coefficients ◽

Aerosol Forcing ◽

Fine Mode ◽

Pristine Forest

Abstract. A long term experiment was conducted in a pristine area in the Amazon forest, with continuous in situ measurements of aerosol optical properties between February 2008 and April 2011, comprising, to our knowledge, the longest database ever in Amazonia. Two types of aerosol particles, with significantly different optical properties were identified: coarse mode predominant biogenic aerosols in the wet season (January–June), naturally released by the forest metabolism, and fine mode dominated biomass burning aerosols in the dry season (July–December), transported from regional fires. Dry particle median scattering coefficients at the wavelength of 550 nm increased from 6.3 Mm−1 to 22 Mm−1, whereas absorption at 637 nm increased from 0.5 Mm−1 to 2.8 Mm−1 from wet to dry season. Most of the scattering in the dry season was attributed to the predominance of fine mode particles (40–80% of PM10 mass), while the enhanced absorption coefficients are attributed to the presence of light absorbing aerosols from biomass burning. As both scattering and absorption increased in the dry season, the single scattering albedo (SSA) did not show a significant seasonal variability, in average 0.86 ± 0.08 at 637 nm for dry particles. Measured particle optical properties were used to estimate the aerosol forcing efficiency at the top of the atmosphere. Results indicate that in this pristine forest site the radiative balance was dominated by the cloud cover, or, in other words, the aerosol indirect effect predominated over the direct effect, particularly in the wet season. Due to the high cloud fractions, the aerosol forcing efficiency was below −3.5 W m−2 in 70% of the wet season days and in 46% of the dry season days. These values are lower than the ones reported in the literature, which are based on remote sensing data. Besides the seasonal variation, the influence of external aerosol sources was observed occasionally. Periods of influence of the Manaus urban plume were detected, characterized by a consistent increase on particle scattering (factor 2.5) and absorption coefficients (factor 5). Episodes of biomass burning and mineral dust particles advection from Africa were observed between January and April, characterized by enhanced concentrations of fine mode (PM2.0), crustal elements (Al, Si, Ti, Fe) and potassium. During these episodes, median particle absorption coefficients increased by a factor of 2, whereas median SSA values decreased by 7%, in comparison to wet season conditions.

Download Full-text

The relationship between aerosol particles chemical composition and optical properties to identify the biomass burning contribution to fine particles concentration: a case study for São Paulo city, Brazil

Environmental Monitoring and Assessment ◽

10.1007/s10661-016-5659-7 ◽

2016 ◽

Vol 189 (1) ◽

Cited By ~ 10

Author(s):

Regina Maura de Miranda ◽

Fabio Lopes ◽

Nilton Évora do Rosário ◽

Marcia Akemi Yamasoe ◽

Eduardo Landulfo ◽

...

Keyword(s):

Optical Properties ◽

Chemical Composition ◽

Biomass Burning ◽

Fine Particles ◽

Aerosol Particles ◽

Sao Paulo ◽

São Paulo ◽

The Relationship

Download Full-text

Aerosol and Cloud Changes during the Corona Lockdown in 2020 – First highlights from the BLUESKY campaign

10.5194/egusphere-egu21-13134 ◽

2021 ◽

Author(s):

Christiane Voigt ◽

Jos Lelieveld ◽

Hans Schlager ◽

Johannes Schneider ◽

Daniel Sauer ◽

...

Keyword(s):

Boundary Layer ◽

Atmospheric Composition ◽

Data Set ◽

The North ◽

Aerosol Mass ◽

Trace Species ◽

Research Aircraft ◽

Fine Mode ◽

Cloud Modeling ◽

Fine Mode Aerosol

Worldwide regulations to control the COVID-19 pandemic caused significant reductions in ground and airborne transportation in spring 2020. This unprecedented situation provided the unique opportunity to directly measure the less perturbed atmosphere, notably near the tropopause, and derive the effects of anthropogenic emissions on atmospheric composition, aerosol, clouds and climate. These changes were investigated during the BLUESKY experiment by the two research aircraft HALO and the DLR Falcon, satellite observations and models. From 16 May to 9 June 2020, the two research aircraft performed 20 flights over Europe and the North Atlantic. Profiles of trace species were measured with an advanced in-situ trace gas, aerosol and cloud payload from the boundary layer to 14 km altitude. Here, we present an overview and selected highlights of the BLUESKY experiment. Continental aerosol profiles show significant reductions in aerosol mass in the boundary layer. The reduced aerosol optical thickness above Germany has also been detected by MODIS and its impact on the colour of the sky is investigated. A specific focus was the detection of aerosol and cirrus changes caused by up to 90% reductions in air traffic. We find reductions in fine mode aerosol in the UTLS at various levels compared to CARIBIC data. In addition, we derive reductions in contrail and cirrus cover using passive and active remote sensing from satellite combined with cloud modeling. The comprehensive data set acquired during the 2020 lockdown period allows better understanding and constraining the anthropogenic influence on the composition of the atmosphere and its impacts on air quality and climate.

Download Full-text

Aircraft observations of the chemical composition and aging of aerosol in the Manaus urban plume during GoAmazon 2014/5

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-10773-2018 ◽

2018 ◽

Vol 18 (14) ◽

pp. 10773-10797 ◽

Cited By ~ 8

Author(s):

John E. Shilling ◽

Mikhail S. Pekour ◽

Edward C. Fortner ◽

Paulo Artaxo ◽

Suzane de Sá ◽

...

Keyword(s):

Chemical Composition ◽

Oxidation State ◽

Biomass Burning ◽

Urban Pollution ◽

Organic Aerosol ◽

Dry Season ◽

Carbon Oxidation ◽

Wet Season ◽

The Mean ◽

American Cities

Abstract. The Green Ocean Amazon (GoAmazon 2014/5) campaign, conducted from January 2014 to December 2015 in the vicinity of Manaus, Brazil, was designed to study the aerosol life cycle and aerosol–cloud interactions in both pristine and anthropogenically influenced conditions. As part of this campaign, the U.S. Department of Energy (DOE) Gulfstream 1 (G-1) research aircraft was deployed from 17 February to 25 March 2014 (wet season) and 6 September to 5 October 2014 (dry season) to investigate aerosol and cloud properties aloft. Here, we present results from the G-1 deployments focusing on measurements of the aerosol chemical composition and secondary organic aerosol (SOA) formation and aging. In the first portion of the paper, we provide an overview of the data and compare and contrast the data from the wet and dry season. Organic aerosol (OA) dominates the deployment-averaged chemical composition, comprising 80 % of the non-refractory PM1 aerosol mass, with sulfate comprising 14 %, nitrate 2 %, and ammonium 4 %. This product distribution was unchanged between seasons, despite the fact that total aerosol loading was significantly higher in the dry season and that regional and local biomass burning was a significant source of OA mass in the dry, but not wet, season. However, the OA was more oxidized in the dry season, with the median of the mean carbon oxidation state increasing from −0.45 in the wet season to −0.02 in the dry season. In the second portion of the paper, we discuss the evolution of the Manaus plume, focusing on 13 March 2014, one of the exemplary days in the wet season. On this flight, we observe a clear increase in OA concentrations in the Manaus plume relative to the background. As the plume is transported downwind and ages, we observe dynamic changes in the OA. The mean carbon oxidation state of the OA increases from −0.6 to −0.45 during the 4–5 h of photochemical aging. Hydrocarbon-like organic aerosol (HOA) mass is lost, with ΔHOA∕ΔCO values decreasing from 17.6 µg m−3 ppmv−1 over Manaus to 10.6 µg m−3 ppmv−1 95 km downwind. Loss of HOA is balanced out by formation of oxygenated organic aerosol (OOA), with ΔOOA∕ΔCO increasing from 9.2 to 23.1 µg m−3 ppmv−1. Because hydrocarbon-like organic aerosol (HOA) loss is balanced by OOA formation, we observe little change in the net Δorg∕ΔCO values; Δorg∕ΔCO averages 31 µg m−3 ppmv−1 and does not increase with aging. Analysis of the Manaus plume evolution using data from two additional flights in the wet season showed similar trends in Δorg∕ΔCO to the 13 March flight; Δorg∕ΔCO values averaged 34 µg m−3 ppmv−1 and showed little change over 4–6.5 h of aging. Our observation of constant Δorg∕ΔCO are in contrast to literature studies of the outflow of several North American cities, which report significant increases in Δorg∕ΔCO for the first day of plume aging. These observations suggest that SOA formation in the Manaus plume occurs, at least in part, by a different mechanism than observed in urban outflow plumes in most other literature studies. Constant Δorg∕ΔCO with plume aging has been observed in many biomass burning plumes, but we are unaware of reports of fresh urban emissions aging in this manner. These observations show that urban pollution emitted from Manaus in the wet season forms less particulate downwind as it ages than urban pollution emitted from North American cities.

Download Full-text

Biomass-burning and urban emission impacts in the Andes Cordillera region based on in-situ measurements from the Chacaltaya observatory, Bolivia (5240 m a.s.l.)

10.5194/acp-2019-510 ◽

2019 ◽

Cited By ~ 1

Author(s):

Chauvigné Aurélien ◽

Diego Aliaga ◽

Marcos Andrade ◽

Patrick Ginot ◽

Radovan Krejci ◽

...

Keyword(s):

Optical Properties ◽

Aerosol Particle ◽

Biomass Burning ◽

Dry Season ◽

Wet Season ◽

Stable Layer ◽

La Paz ◽

Extinction Coefficients ◽

El Alto

Abstract. We present the variability of aerosol particle optical properties measured at the global Atmosphere Watch (GAW) station Chacaltaya (5240 m a.s.l.). The in-situ mountain site is ideally located to study regional impacts of the densely populated urban area of La Paz/El Alto, and the intensive activity in the Amazonian basin. Four year measurements allow to study aerosol particle properties for distinct atmospheric conditions as stable and turbulent layers, different airmass origins, as well as for wet and dry seasons, including biomass-burning influenced periods. The absorption, scattering and extinction coefficients (median annual values of 0.74, 12.14 and 12.96 Mm−1 respectively) show a clear seasonal variation with low values during the wet season (0.57, 7.94 and 8.68 Mm−1 respectively) and higher values during the dry season (0.80, 11.23 and 14.51 Mm−1 respectively). These parameters also show a pronounced diurnal variation (maximum during daytime, minimum during night-time, as a result of the dynamic and convective effects of leading to lower atmospheric layers reaching the site during daytime. Retrieved intensive optical properties are significantly different from one season to the other, showing the influence of different sources of aerosols according to the season. Both intensive and extensive optical properties of aerosols were found to be different among the different atmospheric layers. The particle light absorption, scattering and extinction coefficients are in average 1.94, 1.49 and 1.55 times higher, respectively, in the turbulent layer compared to the stable layer. We observe that the difference is highest during the wet season and lowest during the dry season. Using wavelength dependence of aerosol particle optical properties, we discriminated contributions from natural (mainly mineral dust) and anthropogenic (mainly biomass-burning and urban transport or industries) emissions according to seasons and tropospheric layers. The main sources influencing measurements at CHC are arising from the urban area of La Paz/El Alto, and regional biomass-burning from the Amazonian basin. Results show a 28 % to 80 % increase of the extinction coefficients during the biomass-burning season with respect to the dry season, which is observed in both tropospheric layers. From this analyse, long-term observations at CHC provides the first direct evidence of the impact of emissions in the Amazonian basin on atmospheric optical properties far away from their sources, all the way to the stable layer.

Download Full-text

Biomass burning and urban emission impacts in the Andes Cordillera region based on in situ measurements from the Chacaltaya observatory, Bolivia (5240 m a.s.l.)

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-14805-2019 ◽

2019 ◽

Vol 19 (23) ◽

pp. 14805-14824

Author(s):

Aurélien Chauvigné ◽

Diego Aliaga ◽

Karine Sellegri ◽

Nadège Montoux ◽

Radovan Krejci ◽

...

Keyword(s):

Optical Properties ◽

Biomass Burning ◽

Light Absorption ◽

Amazon Basin ◽

Dry Season ◽

La Paz ◽

Extinction Coefficients ◽

Aerosol Emission ◽

El Alto ◽

The Impact

Abstract. This study documents and analyses a 4-year continuous record of aerosol optical properties measured at the Global Atmosphere Watch (GAW) station of Chacaltaya (CHC; 5240 m a.s.l.), in Bolivia. Records of particle light scattering and particle light absorption coefficients are used to investigate how the high Andean Cordillera is affected by both long-range transport and by the fast-growing agglomeration of La Paz–El Alto, located approximately 20 km away and 1.5 km below the sampling site. The extended multi-year record allows us to study the properties of aerosol particles for different air mass types, during wet and dry seasons, also covering periods when the site was affected by biomass burning in the Bolivian lowlands and the Amazon Basin. The absorption, scattering, and extinction coefficients (median annual values of 0.74, 12.14, and 12.96 Mm−1 respectively) show a clear seasonal variation with low values during the wet season (0.57, 7.94, and 8.68 Mm−1 respectively) and higher values during the dry season (0.80, 11.23, and 14.51 Mm−1 respectively). The record is driven by variability at both seasonal and diurnal scales. At a diurnal scale, all records of intensive and extensive aerosol properties show a pronounced variation (daytime maximum, night-time minimum), as a result of the dynamic and convective effects. The particle light absorption, scattering, and extinction coefficients are on average 1.94, 1.49, and 1.55 times higher respectively in the turbulent thermally driven conditions than the more stable conditions, due to more efficient transport from the boundary layer. Retrieved intensive optical properties are significantly different from one season to the other, reflecting the changing aerosol emission sources of aerosol at a larger scale. Using the wavelength dependence of aerosol particle optical properties, we discriminated between contributions from natural (mainly mineral dust) and anthropogenic (mainly biomass burning and urban transport or industries) emissions according to seasons and local circulation. The main sources influencing measurements at CHC are from the urban area of La Paz–El Alto in the Altiplano and from regional biomass burning in the Amazon Basin. Results show a 28 % to 80 % increase in the extinction coefficients during the biomass burning season with respect to the dry season, which is observed in both tropospheric dynamic conditions. From this analysis, long-term observations at CHC provide the first direct evidence of the impact of biomass burning emissions of the Amazon Basin and urban emissions from the La Paz area on atmospheric optical properties at a remote site all the way to the free troposphere.

Download Full-text

The characteristics of atmospheric brown carbon in Xi'an, inland China: sources, size distributions and optical properties

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-2017-2020 ◽

2020 ◽

Vol 20 (4) ◽

pp. 2017-2030 ◽

Cited By ~ 3

Author(s):

Can Wu ◽

Gehui Wang ◽

Jin Li ◽

Jianjun Li ◽

Cong Cao ◽

...

Keyword(s):

Optical Properties ◽

Biomass Burning ◽

Isotope Composition ◽

Stable Carbon Isotope ◽

Urban Atmosphere ◽

Semiarid Region ◽

Chemical Compositions ◽

Brown Carbon ◽

Polycyclic Aromatic ◽

Fine Mode

Abstract. To investigate the characteristics of atmospheric brown carbon (BrC) in the semiarid region of East Asia, PM2.5 and size-resolved particles in the urban atmosphere of Xi'an, inland China, during the winter and summer of 2017 were collected and analyzed for optical properties and chemical compositions. Methanol extracts (MeOH extracts) were more light-absorbing than water extracts (H2O extracts) in the optical wavelength of 300–600 nm and well correlated with nitrophenols, polycyclic aromatic hydrocarbons (PAHs) and oxygenated PAHs (r > 0.78). The light absorptions (absλ=365 nm) of H2O extracts and MeOH extracts in winter were 28±16 and 49±32 M m−1, respectively, which are about 10 times higher than those in summer, mainly due to the enhanced emissions from biomass burning for house heating. Water-extracted BrC predominately occurred in the fine mode (< 2.1 µm) during winter and summer, accounting for 81 % and 65 % of the total absorption of BrC, respectively. The light absorption and stable carbon isotope composition measurements showed an increasing ratio of absλ=365 nm-MeOH to absλ=550 nm-EC along with an enrichment of 13C in PM2.5 during the haze development, indicating an accumulation of secondarily formed BrC (e.g., nitrophenols) in the aerosol aging process. Positive matrix factorization (PMF) analysis showed that biomass burning, fossil fuel combustion, secondary formation, and fugitive dust are the major sources of BrC in the city, accounting for 55 %, 19 %, 16 %, and 10 % of the total BrC of PM2.5, respectively.

Download Full-text

Characterizing two distinct biomass burning regimes over Southeast Asia and their impacts on regional air quality

10.5194/egusphere-egu2020-7653 ◽

2020 ◽

Author(s):

Margaret Marvin ◽

Paul Palmer ◽

Fei Yao ◽

Barry Latter ◽

Richard Siddans ◽

...

Keyword(s):

Air Quality ◽

Southeast Asia ◽

Biomass Burning ◽

Atmospheric Chemistry ◽

Agricultural Waste ◽

Critical Evaluation ◽

Dry Season ◽

Mitigation Strategies ◽

Atmospheric Composition ◽

Regional Air Quality

Mainland and maritime Southeast Asia is home to more than 655 million people, representing nearly 10% of the global population. The dry season in this region is typically associated with intense biomass burning activity, which leads to a significant increase in surface air pollutants that are harmful to human health, including ozone (O3) and fine (radii smaller than 2.5 microns) particulate matter (PM2.5). Latitude-based differences in dry season timing and land use distinguish two regional biomass burning regimes: (1) agricultural waste burning on the peninsular mainland from February through April and (2) coastal peat burning across the equatorial islands in September and October. The type and amount of material burned determines the chemical composition of emissions and subsequently their impact on regional air quality. Understanding the individual and collective roles of these biomass burning regimes is a crucial step towards developing effective air quality mitigation strategies for Southeast Asia. Here, we use the nested GEOS-Chem atmospheric chemistry transport model (horizontal resolution of 0.25&#176; x 0.3125&#176;) to simulate fire-atmosphere interactions over Southeast Asia during March and September of 2014, when emissions peak from the two regional burning seasons. Based on our analysis of model output, we report how these two distinct biomass burning regimes impact the photochemical environment over Southeast Asia and what the resulting consequences are for surface air quality. We will also present a critical evaluation of our model using ground-based and satellite observations of atmospheric composition across the region.

Download Full-text